间接蒸发冷却换热器模型开发及验证

Model Development and Validation for Heat exchanger of Indirect Evaporative Cooler

为了研究间接蒸发冷却换热器通过非直接接触方式将二次空气直接蒸发的冷量传递给一次空气的换热过程。本文采用有限元法构建了间接蒸发冷却换热器模型,根据换热器入口条件迭代计算一次空气和二次空气的出口状态,引入了换热器表面可湿性系数及空气入口状态计算以提升模型精度,通过实验数据验证,模型在干工况的平均相对误差为1.99%,在湿工况的平均相对误差为3.95%。同时基于换热器模型分析了换热芯结构参数对换热量的影响。结果表明换热芯宽度减小21.3%会导致换热量下降20.4%,换热芯长度减小21.3%会导致换热量下降9.3%,换热芯高度减小50%会导致换热量下降50.1%,换热板厚度增大50%会导致换热量下降1.4%,在实际应用中需结合制冷量需求合理设计换热芯结构尺寸。

The indirect evaporative cooler(IEC)transfers the evaporative cooling from secondary air to the primary air with indirect contact heat transfer method.In this paper,a mathematical model is developed for the IEC system based on infinitesimal element method.In the model,the coefficient of wettability and the secondary air inlet state are introduced to improve the accuracy of the model.The mean relative error of the model is 1.99%in dry condition and 3.95%in wet condition.In addition,the effect of the heat exchanger structure on the heat transfer is also analyzed.The results indicate that 21.3%decrease in the width of the heat exchanger leads to 20.4%decrease in heat transfer,21.3%decrease in the length of the heat exchanger leads to 9.3%decrease in heat transfer,50%decrease in the height of the heat exchanger leads to 50.1%decrease in heat transfer,and 50%increase in the thickness of the heat exchanger plate leads to 1.4%decrease in heat transfer.Therefore,the heat exchanger should be reasonably designed in conjunction with the cooling capacity requirements.